This invention relates to drives for vehicles, and more particularly, to a drive which offers the driver a choice between drive by an elecric motor and drive by an internal combustion engine.
The recent decrease in supplies of petroleum has brought about a consequent increase in the price of refined products, such as gasoline and diesel fuel. The increases in prices of fuel have brought about a demand for more efficient engines and motor vehicles which conserve the use of fuel.
It is recognized that the internal combustion engine commonly found in motor vehicles today is inefficient at low speeds. Electric motors, on the other hand, are comparatively more efficient at lower speeds, but not at higher speeds. Thus, it has been proposed that a vehicle utilize an electric motor for low speeds and an internal combustion engine for higher speeds. Such a drive is known in its broadest sense from the British Pat. No. 393,311 as well as a similar design in German letters of disclosure No. 21 33 485 classified in B60L, 13/00. In a vehicle with a dual drive, the electric motor can be used in speed and rotational ranges within which the efficiency of the internal combustion engine is relatively low.
Additionally, a starter motor for the internal combustion engine may be eliminated in a dual drive vehicle since the electric motor can also perform this function.
Swiss Pat. No. 222,098 discloses a drive with an internal combustion engine and an electric motor which also serves as a starter motor. The driver actuates a single lever to start the vehicle, and when a predetermined speed is reached, the internal combustion engine is switched in and the electric motor is cut out.